In the fields of solar batteries, light emitting devices, touch panels, and the like, metal oxide films are formed on substrates. Conventionally, as non-vacuum film formation techniques for forming a metal oxide film on a substrate, there are techniques disclosed in Patent Documents 1, 2 and 3.
In the technique disclosed in Patent Document 1, a metal oxide film is formed on a substrate by bringing the substrate which is heated into contact with a solution in which metal salt or a metal complex is dissolved. In this case, the solution contains at least one of an oxidizing agent and a reducing agent.
In the technique disclosed in Patent Document 2, tetrabutyltin or a tin tetrachloride solution with hydrogen peroxide added as an oxidizing agent is sprayed onto a preheated substrate and decomposed by heat. Then, after the substrate temperature decreased by the spraying of the solution is recovered, the solution is repeatedly sprayed. By this operation, a tin oxide thin film is grown on a surface of the substrate.
In the technique disclosed in Patent Document 3, a thin film material dissolved in a volatile solvent is intermittently sprayed from the above onto a substrate which is held while being heated and a transparent conductive film is thereby formed on a surface of the substrate. In this case, the intermittent spray is a high velocity pulsed intermittent spray in which the spraying time is 100 ms or less at a time.